If you’re on the stock firmware it should be easy, you can most likely use the web interface to upgrade the firmware. Just upload your file and press upgrade..
If you’ve already flashed a custom firmware on your router or if the web interface won’t work, you’ll most likely have to use tftp. I will explain how to do this in OSX but the procedure on the router will be the same no matter the OS you’re using on your computer. The tricky part is to send the file through tftp to your router at the right moment.
1. Download the firmware you want to install, put it in your home folder /Users/yourname/
2. plug the computer into LAN port 1 on the router
set the the computer to a static IP of 192.168.1.2 in system->network->”Using DHCP with manual address”
3. Open the terminal and type:
4. In a text document copy and paste the code below and change your-firmware.img to the file name of your firmware. Now copy the entire code including the empty line break beneath the code and switch to the terminal (do not paste the code yet)
5. Now go to your router and turn it off by pressing the button on the back side.
Take a needle or whatever you can use to push the reset button on the bottom of the router and be prepared to press the button. Power on the router again. First the power led will light up and then all the lights should blink at once. When they do, press the reset button and hold it until the Power LED begins to flash orange and then tirm green. Now release the reset button and go as quickly as you can back to your computer
6. paste your code in the terminal. It should execute by itself since you copied the line break beneath the code. You only have a few seconds to do this or the router will boot up like normal so be quick. If it works you should see something like this
Sent 1563564 bytes in 8.0 seconds
7. If it was successful the router will now write the image which will take a while. Just be patient. For me it took 4 minutes before the router started showing life signs again.
Now, as usual, I’m not responsible if you break anything.